There are various devices known in the art for monitoring heart function. Many of these devices typically function by analyzing signals such as an electrocardiogram signal, which can be representative of heart function.
There is a need to identify patients at high risk for life-threatening arrhythmias.
Various means have been proposed for detecting patient susceptibility to arrhythmias. U.S. Pat. No. 5,117,834 discloses one method by which pulses of electromagnetic energy are injected into a patient and the changes in the patient's electrocardiographic signals caused by the injection are recorded. U.S. Pat. No. 5,351,687 is similar in concept to U.S. Pat. No. 5,117,834, but it describes use of a magnetic sensor for use in detecting the cardiographic signals. U.S. Pat. No. 5,555,888 discloses various means for adapting and automatically facilitating the assessment techniques and means similar to that shown in the above patents for determining patient susceptibility to arrhythmias.
Other techniques which are used to analyze cardiac signals for somewhat similar purposes include those known as t-wave alternans and signal-averaged electrocardiograms. Each of these techniques is limited in its application and utility by various factors which are overcome through use of the below described inventions.